Actually, someone is writing a perl-based KB system. :-)

The primary developer is James G. Smith, and it will be used for the mod_perl 2.0 docs & KB. The project homepage is http://sourceforge.net/projects/perlkb/

If you're interested in what he's doing, search the mod_perl list archives from the last month or so and you will find the relevant threads. The current release doesn't do anything yet, but the framework is there and I expect that something useful will be there shortly.